Fish-friendly changes at Nevada dam to help threatened trout

Federal officials walk across the Derby Dam in Wadsworth, Nev.,as Truckee River water flows beneath on Wednesday, Sept. 11, 2019 about 20 miles east of Reno, Nevada. The U.S. Bureau of Reclamation has launched a $23.5 million fish diversion project to help the threatened Lahontan cutthroat trout pass upstream to their native spawning grounds cutoff since the dam was built in 1905. Before that, the trout would migrate from Pyramid Lake in the high desert 120 miles upstream to spawn in Lake Tahoe.
Scott Sonner
AP Photo

WADSWORTH, Nev.

Federal officials are making fish-friendly modifications to a northern Nevada dam that for more than a century has blocked off native spawning grounds for a threatened trout species that once migrated 120 miles (193 kilometers) upstream from a high-desert lake to the alpine waters of Lake Tahoe.

Officials for the U.S. Bureau of Reclamation, Fish and Wildlife Service and Pyramid Lake Paiute Tribe broke ground Tuesday for a $23.5 million fish-passage project to help Lahontan cutthroat trout navigate the Truckee River's Derby Dam about 20 miles (32 kilometers) east of Reno.

As soon as next fall, fish screens in a bypass canal longer than a football field will allow the trout — once believed to have gone extinct — to get past the dam for the first time since it was built in 1905.

Commissioned by President Theodore Roosevelt, the dam was part of the first major irrigation system established in the West to "help make the desert bloom," diverting water to farmers and ranchers in a region where only about 5 inches of rain falls annually.

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"This day is 100 years in the making," said Jody Holzworth, deputy regional director of the U.S. Fish and Wildlife Service. "The fish screen will allow this iconic species to travel beyond Derby Dam, from Pyramid Lake to their spawning grounds, for the first time in more than a century."

Lahontan cutthroat trout, the state fish of Nevada and largest trout in North America, used to grow as large as 60 pounds (27 kilograms) when they would climb 2,500 feet (762 meters) through mountain river canyons to Lake Tahoe, elevation 6,228 feet (1,898 meters).

Tribal leaders and state and federal wildlife officials have been working for two decades to restore the fishery in Pyramid Lake — a remnant of ancient Lake Lahontan, an inland sea that covered 8,450 square miles (21,885 sq. kilometers) of western Nevada during the Ice Age. The Lahontan cutthroat trout also are native to parts of Oregon, Utah and Wyoming.

Dan Mosley, executive director of the Pyramid Lake Fishery for the Pyramid Lake Paiute Tribe, said the tribe has a long history of "fighting for the fish."

"They are really important in our stories and our culture," Mosley said.

In recent years, the fish have made their way several miles upstream from Pyramid Lake but haven't been able to get past the Derby Dam.

The trout was thought to have gone extinct in the 1940s and was listed as threatened in 1970. But a remnant population later was discovered in a small brook on Pilot Peak along the Nevada-Utah border.

Beginning in 2006, that population has been used to successfully restock Pyramid Lake, where Holzworth said anglers now regularly catch cutthroats as big as 25 pounds (11 kilograms).

Cutthroats successfully spawned in Pyramid Lake in 2014 for the first time in 80 years and this year, 775 successfully spawned in the river between the lake and dam.

The bypass canal will include an 80-foot-wide, 390-foot-long horizontal fish screen — actually a metal plate with slots that pushes water down through the water system while sending the fish and other debris through the side channel.

The Farmers Irrigation District of Hood River, Oregon first developed what is now known as the "Farmers Screen" after severe flooding in 1996. The district licensed the patent to the nonprofit Farmers Conservation Alliance which since has completed 50 similar projects in several Western states.

This one is the largest and the first the Bureau of Reclamation has commissioned.

"It's a milestone in the history of Reclamation," Bureau Commissioner Brenda Burman said Wednesday, "a critical investment in modernizing our infrastructure to provide reliable water supplies in an environmentally sound manner."